Microfluidic processes often employ the use of an emulsion, which contains drops of a dispersed liquid phase surrounded by an immiscible continuous liquid phase. Drops may be used as reaction vessels for chemical or biological reactions, as storage vessels, and/or as a method to isolate and compartmentalize molecules, such as chemical or biological elements. With proper chemistry such as surfactants on the surface of the emulsion, drops may be made “stable,” meaning they are substantially prevented form mixing and merging when in contact with each other. This stability allows one to create a population or library of drops composed of different chemical or biological components that may be stored in the approximately same volume of space without mixing or contamination between and/or among the components of one drop and another.
In some cases, drops within a microfluidic device flow within microfluidic channels in order to access different areas of the device. As the drops flow throughout the channels within the microfluidic device, the drops often mix and rearrange themselves, resulting in the loss of defined arrangement of drops, causing issues downstream in drop packing for a number of processes, drop detection and data analysis. In some cases, the diameter of a particular channel or portion of a channel (e.g., a widening or narrowing channel) is a significant factor associated with the problem in maintaining the arrangement of drops and drop packing within a channel. Accordingly, there is a need for a system and method for maintaining the arrangement of drops within a microfluidic channel via drop confinement.